


An Unusual Deduction

by poppetawoppet



Category: Sherlock (TV)
Genre: Aliens, Crack, M/M, Mpreg
Language: English
Status: Completed
Published: 2015-09-07
Updated: 2015-09-07
Packaged: 2018-04-19 11:50:23
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,300
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4745270
Author URL: https://archiveofourown.org/users/poppetawoppet/pseuds/poppetawoppet
Summary: <blockquote class="userstuff">
              <p>John is sick. Sherlock's deduction as to what is wrong is a surprise and changes their relationship forever.</p>
            </blockquote>





	An Unusual Deduction

**Author's Note:**

> This is my very first fic in the fandom. _And I wrote crack mpreg_ (Every fandom needs crack mpreg). Anyway thank you to [](http://ginbitch.livejournal.com/profile)[**ginbitch**](http://ginbitch.livejournal.com/) for beta/Brit-picking: any mistakes are mine, [](http://cabayuki.livejournal.com/profile)[**cabayuki**](http://cabayuki.livejournal.com/) for conning me into writing fic for this fandom, and apologies to [](http://phaballa.livejournal.com/profile)[](http://phaballa.livejournal.com/)**phaballa** for stealing some of her ideas.

John watches Sherlock pace around the room. This is not an unusual activity for either of them, except that it is about four in the morning, and John is lying on the couch with a cool washcloth on his forehead and the taste of bile still in his mouth.

"I could just ring a doctor," John says.

"You're a doctor and you haven't figured out what's wrong with you," Sherlock counters, and resumes his pacing.

John sits up, as the nausea has already passed. "It's just a bug."

"It is not a bug and I think I may have the answer!"

"Oh really?" John crosses his arms. "Then tell me _Doctor_ Holmes, whatever is wrong with me?"

"There's no need to be like that," Sherlock frowns.

John knows it's only because Sherlock wants to astound him, and John isn't playing along.

"I'm tired, it's early in the morning and I just threw up the excellent toad-in-the-hole Mrs. Hudson made us last night. So please, get _on_ with it Sherlock."

Sherlock grins, and John couldn't help but grin back, because, well, it's _Sherlock_ and John can't help but smile at him.

"Well, after reviewing all of your symptoms, even the ones you refuse to list as symptoms, I have come to one conclusion," Sherlock pauses (as he always does), "you're pregnant."

John blinks and bursts into laughter. "Oh that's perfect Sherlock. Good joke. Now really, what's wrong with me?"

Sherlock's face falls. "I told you. You're pregnant."

John stands. "That's impossible Sherlock. I am a man. Men do not get pregnant!"

"Minor detail. Everything else fits."

Sherlock isn't saying something, but John is too annoyed to dig deeper just yet.

"Fine. Prove it to me."

Sherlock grins again, but it is not returned.

"First: the morning sickness."

"While I realise that morning sickness can come at all hours, you'll have to do better than that," John responds.

"There is no apparent reason for your sickness. There are no traces of any viruses or bacteria in your blood—"

"You took _blood_?"

Sherlock shrugs, "You wouldn't give it to me, so yes."

"I'm moving back to my room. This is insane."

"John. Please."

There is something in Sherlock's voice, and John stops in the doorway.

"Fine. Go on with this insanity then."

"Good!" Sherlock rubs his hands together. "Where was I? Ah yes, there was the unprotected sex—"

"Sherlock," John warns.

_Sherlock is inside him, skin against skin, driving deeper, calling out John's name—_

Sherlock says nothing for a moment and John knows exactly where his mind went. John may not have been able to follow Sherlock's mind on all occasions, but when it came to the two of them, their brains run on fairly similar wavelengths.

"Anyway, we could talk about your cravings—"

"I do not have cravings!"

"What about that side trip in Cambridge in the middle of a case just to buy some Branston pickle? 'Not the squeezy kind, Sherlock, I really must have the stuff in the jar'," Sherlock says. "In the middle of a case, I say."

"I really fancied a cheese and Branston pickle sandwich."

"Yes, but every day for a week?"

"I had to get rid of it before you put another body part in the fridge!"

John hears his voice rising, but this was completely ridiculous.

"You still don't believe me do you?" Sherlock shakes his head. "I wasn't going to use this, but what about your breasts? They've been terribly sensitive."

John splutters, "I don't have—"

"Your nipples then."

"They have not—"

Sherlock is across the room in a flash, crowding John into the wall.

"Oh really?" Sherlock whispers, "I seem to remember differently."

John swallows.

_Sherlock's hands are everywhere, pale, thin and agile. John likes it when Sherlock touches him, but this is so much more. Sherlock's thumb rubs across John's nipple. John moans, because it feels different for some reason. Sherlock raises an eyebrow._

_"Well then, this is something I have to explore,"_

_Then he lowers his head and all is lost except for John's cries._

"Maybe if you didn't play with them so much, they wouldn't be sensitive," John finally responds.

"But you like when I play with them. Should I stop?"

"No!" John bites his lip. "No. I mean—"

"Last night was different than normal. Also you are tired all the time and then two days ago, when we closed the Simms case, you actually smelled blood before I did. All clear signs of pregnancy."

"Sherlock. Do I have to take a pregnancy test to prove you wrong?"

"Actually—"

John sighs. "You bought some home didn't you?"

Sherlock nods, sweeping into the other room and producing ten different kinds of tests.

"Since you are peeing so often—which by the way is a sign of _pregnancy_ —I thought more would be better."

"Fine," John says, and grabs the bag out of Sherlock's hands. "I'll do this. But no help from you. You have a habit of twisting things so they go your way."

"I do not."

"Not on cases, no, but when it comes to me, yes."

Sherlock says nothing, and John retreats to the bathroom.

"By the way John, you've been very irritable lately. You do know that sudden mood swings—"

"Sherlock?"

"Yes?"

"Shove off. I'm taking these stupid tests. Just let it alone until they're done."

Sherlock nods and goes to sit. He picks up his violin, picking out nursery rhymes, from what John can tell from the toilet.

John stares at the boxes and sighs. This was so incredibly _stupid_.

*

_Ten minutes later_

"John? John?" Sherlock pounds at the door. "Surely the tests are done by now!"

John ignores the noise and stares at the sticks and bars and other devices. It had to be a defect. Ten defects in ten very different tests all bought at different stores, if John knew Sherlock.

"I'll be right out," John manages to say.

He is pregnant, although he isn't sure how it could have possibly happened. He has to call Harry, but his phone is outside and Sherlock is outside, and John doesn't know how to handle it.

John finally stands. He lived through Afghanistan. Surely he can handle a baby.

"Sherlock?" John peers out the door.

"I was right wasn't I?"

"Sherlock—"

"I didn't think it was possible—"

"OF COURSE IT ISN'T POSSIBLE I AM A MAN. YOU ARE A MAN. THIS SHOULD NOT BE POSSIBLE!!" John explodes.

Sherlock looks at him for a long time. "Well, not exactly."

"Excuse me?"

Sherlock walks over to his bookcase and retrieves something in a plain dust jacket. He hands the book to John, who opens the cover and reads:

"An Easy Guide to Living With Humans: Dos and Don'ts for Our Stay on Earth?" John read aloud. "Sherlock, what are you implying?"

"Well if you skip to the sex section it would make this easier, but I'm about one-fifth alien, and I shouldn't have possibly been able to get pregnant, but apparently in same sex situations, certain variables kick in. I just thought my human blood dominated for us to be safe. I suppose I was wrong," Sherlock says this with less pain that John ever imagined him doing so. "This is fascinating. I mean I've always wanted to observe this sort of thing up close, but I didn't think I would get all the details. Oh I am so excited, it is—"

"Sherlock."

"What?"

John feels he should be used to Sherlock's lack of tact in certain situations, but it's four in the morning; John's hungry and tired and he just wants to curl back into bed.

"This is a baby, not an experiment—"

"But John—"

"This is _our_ baby, Sherlock. And I refuse to make it into one of your games."

John brushes past Sherlock, grabbing a coat on the way out. Sherlock does not follow.

John is not surprised.

*

John doesn't even realize that he's on his way to Harry's until he reaches her door. He knocks anyway, because there isn't really anyone else he can talk to about this. Sarah will probably hospitalise him, Lestrade will laugh at him, and Mrs. Hudson will pass it off as some sort of weird thing he and Sherlcok are doing just to tire her out. Or something like that. So Harry it is.

"John?"

"I know we don't really get on but this is an emergency. I don't know who else to talk to."

Harry lets him in and makes him tea. John sits on her couch, saying nothing at first, and then she asks after Sherlock and the whole tale comes spilling out.

Harry blinks, then a broad grin crosses her face. "I always thought I'd be the first, but I'm so happy for you!"

"I'm happy too, I think, I just can't understand how this happened!" John says.

"Well, you had unprotected sex, silly. "

"I'm a _man!_ " John yells and gets up.

"But—you have the book."

John pauses in putting his coat on. He has forgotten the book in the trip to Harry's, it's still tucked into the pocket of his jacket.

"You mean you've seen this book before?"

Harry nods. "You mean someone else gave that to you?"

"Sherlock did. He says he's one-fifth alien."

Harry beams. "Oh. Well then of course he was surprised. We're aliens. Half actually. Mum was an alien. Dad was human. I can't believe she didn't tell you."

"It never came up in any of our conversations," John is astounded that he is even going along with this nonsense. Then again ten positive pregnancy tests cannot be wrong. "So. This manual explains everything?"

"Should do. Do you want to stay for lunch? I can show you some awesome stuff to tell you about."

"Like?"

"Well, I'm sure you already noticed, um, you know I'll let you read about that."

"What?" John's brain is trying to work, but there has been too much weird information thrown at him.

"Read the section on sex. I'll put together something for us."

John stares at the book, and cracks it open.

_Sex and Humans:_

_Now obviously mixing with humans is necessary as they outnumber us. However one must be careful, as we have noticed some strange effects of interactions. First: if one chooses to have sex with an unmated human, make sure to use what they call "protection". This is of utmost importance no matter the sex of the human, because any unprotected sex will result in a child. (See also **Pregnancy and You!** )._

_…._

_One will also note that stamina is not an issue. Please be careful, because humans are more delicate than us, and break easily! However, if your human is strong and healthy, there should be a mutually satisfying relationship—_

John puts the book down for a second. Well that explained a lot of things in his life already. Perhaps the section on pregnancy….

_Pregnancy and You!:_

_Males: Now understand that on our own world mating was much more complicated, and the carrying of children went either way. (See also: Biology). So those of you born male do have the ability to carry children. Do not fret about birth though, because if you can find a female to incubate your child, everything will be fine! If not, then things may get sticky and you may have to disappear and revert to your natural form to give birth._

_Also, if you are not completely alien, this is essential: You cannot transfer your baby. We know this is a difficult situation, but human biology is even more complicated than ours. The bonus is the pregnancy is accelerated and you will give birth within four months of conception. Bad news: you probably should arrange a vacation for the last two weeks. Consult a local alien doctor for more information._

"You okay John?"

"I'm having a baby with my best friend who thinks this is the greatest experiment ever and now I just found out I'm half alien and the birth of said baby may or may not be the most painful experience of my life. I'm good. Really."

Harry smiles and pats John on the back. "I know we haven't been the best of friends, but I'm here. Really I am. And give Sherlock time. You know he's a little slow when it comes to matters of the heart. How about we have lunch and then I give you the number of a good doctor in your area?"

John nods and follows Harry into the kitchen, clutching the book tightly.

*

Sherlock calls exactly fifteen minutes after lunch is over.

"Please John. Come home."

There is so much more than those four words, and John curses himself for bending under such a weak apology, but it's Sherlock, and well, John needs 221B right now, because it's the only normal thing he can think of. (The fact that he wants to go home and see what appendages are in what appliance tells John his sense of normal may be slightly skewed, but then again, he is pregnant with a half alien baby. Normal isn't in his vocabulary.)

"Call me, okay John?"

John nods at Harry, and for once a visit hasn't devolved into an argument over the future, or alcohol, or any of the petty things that have kept them apart. John rides home in silence, a strange smile on his face. He slowly climbs the stairs, glad Mrs. Hudson is out at the grocery, and he pauses in front of his door.

He prepares himself for any sort of ridiculousness Sherlock comes up with, because John just wants to sleep in his own bed, and maybe to use his new found information he has found in reading his manual. John bites his lip and opens the door.

Sherlock is gone.

John sighs and hangs up his coat. He sits on the couch, trying to reason why Sherlock would be gone, but nothing comes to mind. Until the door opens and a big yellow teddy bear comes in, followed by Sherlock.

"The very nice woman at the store said the bigger the bear, the better the apology. I'm not so sure, but I've heard children like large fuzzy things. What do you think John?"

The look on Sherlock's face is a mix of hope, love and confusion, and John smiles.

"I think it's perfect."

Sherlock's answering grin tugs at John's heart. Sherlock sits next to John and takes his hand.

"I can't apologize for this morning. Because that's the way my mind works. But after you left I got to thinking, and well, I realized I'd been a bit daft."

"A bit?" John says.

"All right, a lot."

"Well I can explain a little of the mystery away if you'd like."

Sherlock looks at John. "Oh really?"

"Turns out I'm half alien."

"And here I was thinking you were just really healthy."

John laughs then, for the first time since he woke up puking ten hours ago. "No. So I guess we need to be more careful from now on."

Sherlock nods. "Well that explains that."

John nods. "But how do we explain a baby?"

Sherlock leans over and kisses him, a warm press of the lips that promises so much more: Sherlock's kisses always promise more, but this is different.

"I'm sure we'll think of something."

*

16 things that happen afterwards

1\. They tell Mrs. Hudson they are adopting. She smiles and says "Of course you are!" and begins knitting all sorts of sweaters and blankets and offering babysitting services. "Not that I'm doing it for free, mind you. I'm your housekeeper, not your babysitter."

2\. Sherlock buys enough Branston pickle to feed ten people.

3\. John eats it all.

4\. Molly and Sarah throw a baby shower, in which John bursts into tears, Lestrade gets suspiciously jealous and a mysterious package from Moriarty arrives. It is a sturdy all-terrain pram, with a note that says "Because you never know what sort of situations you'll get in. ~Jim"

5\. John discovers just because Sherlock is only one-fifth alien does not mean some of the benefits have not been passed down. Sherlock insists they have to test it to its fullest possibilities. In the name of science and all. They spend one weekend locked in Sherlock's room, staggering out for food and drink, until Sherlock hauls in a cooler, and then…

6\. Sherlock reveals a sudden need to protect John from everything. It gets to the point where he tries to carry John up the stairs two weeks before the baby is due, and pulls a muscle in his back. John is torn between laughing and kissing Sherlock senseless, so he does both.

7\. The baby comes two days early, and Sherlock is a marvel to watch. He tears around the apartment, forgetting the entire plan of action he and John had laid out the week before. Then he leaves without John, going out on a cold January day without either his coat or his scarf. John takes Sherlock's cold hand, and he calms down.

8\. The baby is a girl, just about 3.5 kilos, with Sherlock's eyes. She doesn't cry at first, merely looks in a way that is so achingly Sherlock that John almost bursts into tears from joy. Then Sherlock cradles her in his arms and John can't look, because she fits there just so, and Sherlock is murmuring nonsense baby talk, despite his insistence on giving the baby a full and wide vocabulary. John files away Sherlock saying coopsie poo for the times he knows Sherlock is going to piss him off.

9\. Ripley Harriet Watson-Holmes (Watson had argued for alphabetical order, but Sherlock had insufferably argued that since John carried the baby, that made him the girl. John had called Sherlock a sexist prig. Sherlock had leaned down and said "Next time I'll carry the baby." John shut up.) comes home to bright pink balloons, a large yellow teddy bear, a zoo themed nursery, and someone's testicle in the refrigerator. John sighs, but at least it wasn't a head. He puts the testicle in a drawer and pulls out the cake.

10\. Sherlock takes to fatherhood quite well, so terribly observant that it is almost annoying. However, when Ripley cries for no reason, or she comes up with something Sherlock cannot figure out, it is quite a relief.

11\. Ripley takes her first steps at a crime scene, reaching up for her daddies and pointing out the large dark stain on the wall. "That's my girl," Sherlock says and winks at John. They begin to discuss how soon they can have another.

12\. Two years, three days and one hour after John discovered he was half alien, Sherlock announces he's expecting. John arranges for a baby sitter so they can celebrate properly.

13\. Edward Thomas Holmes-Watson comes in at 9 kilos and a full head of dark hair. John immediately steals him and starts teaching him the important things: football, how to annoy his other dad. Sherlock rolls his eyes, but he is smiling anyway.

14\. It isn't perfect. Ripley learns quickly her situation is unusual, but she has Sherlock's whimsy and John's toughness and she manages to turn the teasing into something positive. Sherlock spoils her, and John gets to be the bad guy, but he is smiling every day and even though it isn't what he planned for his life, he can't imagine it any other way.

15\. In a strange Romeo and Juliet twist Ripley falls for Andrew Moriarty and they all have to play nice for awhile. Sherlock and John giggle over it when they are alone. Moriarty decides to retire in shame, at least momentarily.

16\. They all live happily ever after. Well, at least until the ships from home arrive. Then things get really interesting.


End file.
